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# Copyright 2019 Google LLC
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# https://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""Routines to check miscellaneous constraints on the IR."""
from compiler.front_end import attributes
from compiler.util import error
from compiler.util import ir_pb2
from compiler.util import ir_util
from compiler.util import resources
from compiler.util import traverse_ir
def _render_type(type_ir, ir):
"""Returns the human-readable notation of the given type."""
assert type_ir.HasField("atomic_type"), (
"TODO(bolms): Implement _render_type for array types.")
if type_ir.HasField("size_in_bits"):
return _render_atomic_type_name(
type_ir,
ir,
suffix=":" + str(ir_util.constant_value(type_ir.size_in_bits)))
else:
return _render_atomic_type_name(type_ir, ir)
def _render_atomic_type_name(type_ir, ir, suffix=None):
assert type_ir.HasField("atomic_type"), (
"_render_atomic_type_name() requires an atomic type")
if not suffix:
suffix = ""
type_definition = ir_util.find_object(type_ir.atomic_type.reference, ir)
if type_definition.name.is_anonymous:
return "anonymous type"
else:
return "type '{}{}'".format(type_definition.name.name.text, suffix)
def _check_that_inner_array_dimensions_are_constant(
type_ir, source_file_name, errors):
"""Checks that inner array dimensions are constant."""
if type_ir.WhichOneof("size") == "automatic":
errors.append([error.error(
source_file_name, type_ir.element_count.source_location,
"Array dimensions can only be omitted for the outermost dimension.")])
elif type_ir.WhichOneof("size") == "element_count":
if not ir_util.is_constant(type_ir.element_count):
errors.append([error.error(source_file_name,
type_ir.element_count.source_location,
"Inner array dimensions must be constant.")])
else:
assert False, 'Expected "element_count" or "automatic" array size.'
def _check_that_array_base_types_are_fixed_size(type_ir, source_file_name,
errors, ir):
"""Checks that the sizes of array elements are known at compile time."""
if type_ir.base_type.HasField("array_type"):
# An array is fixed size if its base_type is fixed size and its array
# dimension is constant. This function will be called again on the inner
# array, and we do not want to cascade errors if the inner array's base_type
# is not fixed size. The array dimensions are separately checked by
# _check_that_inner_array_dimensions_are_constant, which will provide an
# appropriate error message for that case.
return
assert type_ir.base_type.HasField("atomic_type")
if type_ir.base_type.HasField("size_in_bits"):
# If the base_type has a size_in_bits, then it is fixed size.
return
base_type = ir_util.find_object(type_ir.base_type.atomic_type.reference, ir)
base_type_fixed_size = ir_util.get_integer_attribute(
base_type.attribute, attributes.FIXED_SIZE)
if base_type_fixed_size is None:
errors.append([error.error(source_file_name,
type_ir.base_type.atomic_type.source_location,
"Array elements must be fixed size.")])
def _check_that_array_base_types_in_structs_are_multiples_of_bytes(
type_ir, type_definition, source_file_name, errors, ir):
# TODO(bolms): Remove this limitation.
"""Checks that the sizes of array elements are multiples of 8 bits."""
if type_ir.base_type.HasField("array_type"):
# Only check the innermost array for multidimensional arrays.
return
assert type_ir.base_type.HasField("atomic_type")
if type_ir.base_type.HasField("size_in_bits"):
assert ir_util.is_constant(type_ir.base_type.size_in_bits)
base_type_size = ir_util.constant_value(type_ir.base_type.size_in_bits)
else:
fixed_size = ir_util.fixed_size_of_type_in_bits(type_ir.base_type, ir)
if fixed_size is None:
# Variable-sized elements are checked elsewhere.
return
base_type_size = fixed_size
if base_type_size % type_definition.addressable_unit != 0:
assert type_definition.addressable_unit == ir_pb2.AddressableUnit.BYTE
errors.append([error.error(source_file_name,
type_ir.base_type.source_location,
"Array elements in structs must have sizes "
"which are a multiple of 8 bits.")])
def _check_constancy_of_constant_references(expression, source_file_name,
errors, ir):
"""Checks that constant_references are constant."""
if expression.WhichOneof("expression") != "constant_reference":
return
# This is a bit of a hack: really, we want to know that the referred-to object
# has no dependencies on any instance variables of its parent structure; i.e.,
# that its value does not depend on having a view of the structure.
if not ir_util.is_constant_type(expression.type):
referred_name = expression.constant_reference.canonical_name
referred_object = ir_util.find_object(referred_name, ir)
errors.append([
error.error(
source_file_name, expression.source_location,
"Static references must refer to constants."),
error.note(
referred_name.module_file, referred_object.source_location,
"{} is not constant.".format(referred_name.object_path[-1]))
])
def _check_that_enum_values_are_representable(enum_type, type_definition,
source_file_name, errors):
"""Checks that enumeration values can fit in their specified int type."""
values = []
max_enum_size = ir_util.get_integer_attribute(
type_definition.attribute, attributes.ENUM_MAXIMUM_BITS)
is_signed = ir_util.get_boolean_attribute(
type_definition.attribute, attributes.IS_SIGNED)
if is_signed:
enum_range = (-(2**(max_enum_size-1)), 2**(max_enum_size-1)-1)
else:
enum_range = (0, 2**max_enum_size-1)
for value in enum_type.value:
values.append((ir_util.constant_value(value.value), value))
out_of_range = [v for v in values
if not enum_range[0] <= v[0] <= enum_range[1]]
# If all values are in range, this loop will have zero iterations.
for value in out_of_range:
errors.append([
error.error(
source_file_name, value[1].value.source_location,
"Value {} is out of range for {}-bit {} enumeration.".format(
value[0], max_enum_size, "signed" if is_signed else "unsigned"))
])
def _field_size(field, type_definition):
"""Calculates the size of the given field in bits, if it is constant."""
size = ir_util.constant_value(field.location.size)
if size is None:
return None
return size * type_definition.addressable_unit
def _check_type_requirements_for_field(type_ir, type_definition, field, ir,
source_file_name, errors):
"""Checks that the `requires` attribute of each field's type is fulfilled."""
if not type_ir.HasField("atomic_type"):
return
if field.type.HasField("atomic_type"):
field_min_size = (int(field.location.size.type.integer.minimum_value) *
type_definition.addressable_unit)
field_max_size = (int(field.location.size.type.integer.maximum_value) *
type_definition.addressable_unit)
field_is_atomic = True
else:
field_is_atomic = False
if type_ir.HasField("size_in_bits"):
element_size = ir_util.constant_value(type_ir.size_in_bits)
else:
element_size = None
referenced_type_definition = ir_util.find_object(
type_ir.atomic_type.reference, ir)
type_is_anonymous = referenced_type_definition.name.is_anonymous
type_size_attr = ir_util.get_attribute(
referenced_type_definition.attribute, attributes.FIXED_SIZE)
if type_size_attr:
type_size = ir_util.constant_value(type_size_attr.expression)
else:
type_size = None
if (element_size is not None and type_size is not None and
element_size != type_size):
errors.append([
error.error(
source_file_name, type_ir.size_in_bits.source_location,
"Explicit size of {} bits does not match fixed size ({} bits) of "
"{}.".format(element_size, type_size,
_render_atomic_type_name(type_ir, ir))),
error.note(
type_ir.atomic_type.reference.canonical_name.module_file,
type_size_attr.source_location,
"Size specified here.")
])
return
# If the type had no size specifier (the ':32' in 'UInt:32'), but the type is
# fixed size, then continue as if the type's size were explicitly stated.
if element_size is None:
element_size = type_size
# TODO(bolms): When the full dynamic size expression for types is generated,
# add a check that dynamically-sized types can, at least potentially, fit in
# their fields.
if field_is_atomic and element_size is not None:
# If the field has a fixed size, and the (atomic) type contained therein is
# also fixed size, then the sizes should match.
#
# TODO(bolms): Maybe change the case where the field is bigger than
# necessary into a warning?
if (field_max_size == field_min_size and
(element_size > field_max_size or
(element_size < field_min_size and not type_is_anonymous))):
errors.append([
error.error(
source_file_name, type_ir.source_location,
"Fixed-size {} cannot be placed in field of size {} bits; "
"requires {} bits.".format(
_render_type(type_ir, ir), field_max_size, element_size))
])
return
elif element_size > field_max_size:
errors.append([
error.error(
source_file_name, type_ir.source_location,
"Field of maximum size {} bits cannot hold fixed-size {}, which "
"requires {} bits.".format(
field_max_size, _render_type(type_ir, ir), element_size))
])
return
# If we're here, then field/type sizes are consistent.
if (element_size is None and field_is_atomic and
field_min_size == field_max_size):
# From here down, we just use element_size.
element_size = field_min_size
errors.extend(_check_physical_type_requirements(
type_ir, field.source_location, element_size, ir, source_file_name))
def _check_type_requirements_for_parameter_type(
runtime_parameter, ir, source_file_name, errors):
"""Checks that the type of a parameter is valid."""
physical_type = runtime_parameter.physical_type_alias
logical_type = runtime_parameter.type
size = ir_util.constant_value(physical_type.size_in_bits)
if logical_type.WhichOneof("type") == "integer":
integer_errors = _integer_bounds_errors(
logical_type.integer, "parameter", source_file_name,
physical_type.source_location)
if integer_errors:
errors.extend(integer_errors)
return
errors.extend(_check_physical_type_requirements(
physical_type, runtime_parameter.source_location,
size, ir, source_file_name))
elif logical_type.WhichOneof("type") == "enumeration":
if physical_type.HasField("size_in_bits"):
# This seems a little weird: for `UInt`, `Int`, etc., the explicit size is
# required, but for enums it is banned. This is because enums have a
# "native" 64-bit size in expressions, so the physical size is just
# ignored.
errors.extend([[
error.error(
source_file_name, physical_type.size_in_bits.source_location,
"Parameters with enum type may not have explicit size.")
]])
else:
assert False, "Non-integer/enum parameters should have been caught earlier."
def _check_physical_type_requirements(
type_ir, usage_source_location, size, ir, source_file_name):
"""Checks that the given atomic `type_ir` is allowed to be `size` bits."""
referenced_type_definition = ir_util.find_object(
type_ir.atomic_type.reference, ir)
if referenced_type_definition.HasField("enumeration"):
if size is None:
return [[
error.error(
source_file_name, type_ir.source_location,
"Enumeration {} cannot be placed in a dynamically-sized "
"field.".format(_render_type(type_ir, ir)))
]]
else:
max_enum_size = ir_util.get_integer_attribute(
referenced_type_definition.attribute, attributes.ENUM_MAXIMUM_BITS)
if size < 1 or size > max_enum_size:
return [[
error.error(
source_file_name, type_ir.source_location,
"Enumeration {} cannot be {} bits; {} must be between "
"1 and {} bits, inclusive.".format(
_render_atomic_type_name(type_ir, ir), size,
_render_atomic_type_name(type_ir, ir), max_enum_size))
]]
if size is None:
bindings = {"$is_statically_sized": False}
else:
bindings = {
"$is_statically_sized": True,
"$static_size_in_bits": size
}
requires_attr = ir_util.get_attribute(
referenced_type_definition.attribute, attributes.STATIC_REQUIREMENTS)
if requires_attr and not ir_util.constant_value(requires_attr.expression,
bindings):
# TODO(bolms): Figure out a better way to build this error message.
# The "Requirements specified here." message should print out the actual
# source text of the requires attribute, so that should help, but it's still
# a bit generic and unfriendly.
return [[
error.error(
source_file_name, usage_source_location,
"Requirements of {} not met.".format(
type_ir.atomic_type.reference.canonical_name.object_path[-1])),
error.note(
type_ir.atomic_type.reference.canonical_name.module_file,
requires_attr.source_location,
"Requirements specified here.")
]]
return []
def _check_allowed_in_bits(type_ir, type_definition, source_file_name, ir,
errors):
if not type_ir.HasField("atomic_type"):
return
referenced_type_definition = ir_util.find_object(
type_ir.atomic_type.reference, ir)
if (type_definition.addressable_unit %
referenced_type_definition.addressable_unit != 0):
assert type_definition.addressable_unit == ir_pb2.AddressableUnit.BIT
assert (referenced_type_definition.addressable_unit ==
ir_pb2.AddressableUnit.BYTE)
errors.append([
error.error(source_file_name, type_ir.source_location,
"Byte-oriented {} cannot be used in a bits field.".format(
_render_type(type_ir, ir)))
])
def _check_size_of_bits(type_ir, type_definition, source_file_name, errors):
"""Checks that `bits` types are fixed size, less than 64 bits."""
del type_ir # Unused
if type_definition.addressable_unit != ir_pb2.AddressableUnit.BIT:
return
fixed_size = ir_util.get_integer_attribute(
type_definition.attribute, attributes.FIXED_SIZE)
if fixed_size is None:
errors.append([error.error(source_file_name,
type_definition.source_location,
"`bits` types must be fixed size.")])
return
if fixed_size > 64:
errors.append([error.error(source_file_name,
type_definition.source_location,
"`bits` types must be 64 bits or smaller.")])
_RESERVED_WORDS = None
def get_reserved_word_list():
if _RESERVED_WORDS is None:
_initialize_reserved_word_list()
return _RESERVED_WORDS
def _initialize_reserved_word_list():
global _RESERVED_WORDS
_RESERVED_WORDS = {}
language = None
for line in resources.load(
"compiler.front_end", "reserved_words").splitlines():
stripped_line = line.partition("#")[0].strip()
if not stripped_line:
continue
if stripped_line.startswith("--"):
language = stripped_line.partition("--")[2].strip()
else:
# For brevity's sake, only use the first language for error messages.
if stripped_line not in _RESERVED_WORDS:
_RESERVED_WORDS[stripped_line] = language
def _check_name_for_reserved_words(obj, source_file_name, errors, context_name):
if obj.name.name.text in get_reserved_word_list():
errors.append([
error.error(
source_file_name, obj.name.name.source_location,
"{} reserved word may not be used as {}.".format(
get_reserved_word_list()[obj.name.name.text],
context_name))
])
def _check_field_name_for_reserved_words(field, source_file_name, errors):
return _check_name_for_reserved_words(field, source_file_name, errors,
"a field name")
def _check_enum_name_for_reserved_words(enum, source_file_name, errors):
return _check_name_for_reserved_words(enum, source_file_name, errors,
"an enum name")
def _check_type_name_for_reserved_words(type_definition, source_file_name,
errors):
return _check_name_for_reserved_words(
type_definition, source_file_name, errors, "a type name")
def _bounds_can_fit_64_bit_unsigned(minimum, maximum):
return minimum >= 0 and maximum <= 2**64 - 1
def _bounds_can_fit_64_bit_signed(minimum, maximum):
return minimum >= -(2**63) and maximum <= 2**63 - 1
def _bounds_can_fit_any_64_bit_integer_type(minimum, maximum):
return (_bounds_can_fit_64_bit_unsigned(minimum, maximum) or
_bounds_can_fit_64_bit_signed(minimum, maximum))
def _integer_bounds_errors_for_expression(expression, source_file_name):
"""Checks that `expression` is in range for int64_t or uint64_t."""
# Only check non-constant subexpressions.
if (expression.WhichOneof("expression") == "function" and
not ir_util.is_constant_type(expression.type)):
errors = []
for arg in expression.function.args:
errors += _integer_bounds_errors_for_expression(arg, source_file_name)
if errors:
# Don't cascade bounds errors: report them at the lowest level they
# appear.
return errors
if expression.type.WhichOneof("type") == "integer":
errors = _integer_bounds_errors(expression.type.integer, "expression",
source_file_name,
expression.source_location)
if errors:
return errors
if (expression.WhichOneof("expression") == "function" and
not ir_util.is_constant_type(expression.type)):
int64_only_clauses = []
uint64_only_clauses = []
for clause in [expression] + list(expression.function.args):
if clause.type.WhichOneof("type") == "integer":
arg_minimum = int(clause.type.integer.minimum_value)
arg_maximum = int(clause.type.integer.maximum_value)
if not _bounds_can_fit_64_bit_signed(arg_minimum, arg_maximum):
uint64_only_clauses.append(clause)
elif not _bounds_can_fit_64_bit_unsigned(arg_minimum, arg_maximum):
int64_only_clauses.append(clause)
if int64_only_clauses and uint64_only_clauses:
error_set = [
error.error(
source_file_name, expression.source_location,
"Either all arguments to '{}' and its result must fit in a "
"64-bit unsigned integer, or all must fit in a 64-bit signed "
"integer.".format(expression.function.function_name.text))
]
for signedness, clause_list in (("unsigned", uint64_only_clauses),
("signed", int64_only_clauses)):
for clause in clause_list:
error_set.append(error.note(
source_file_name, clause.source_location,
"Requires {} 64-bit integer.".format(signedness)))
return [error_set]
return []
def _integer_bounds_errors(bounds, name, source_file_name,
error_source_location):
"""Returns appropriate errors, if any, for the given integer bounds."""
assert bounds.minimum_value, "{}".format(bounds)
assert bounds.maximum_value, "{}".format(bounds)
if (bounds.minimum_value == "-infinity" or
bounds.maximum_value == "infinity"):
return [[
error.error(
source_file_name, error_source_location,
"Integer range of {} must not be unbounded; it must fit "
"in a 64-bit signed or unsigned integer.".format(name))
]]
if not _bounds_can_fit_any_64_bit_integer_type(int(bounds.minimum_value),
int(bounds.maximum_value)):
if int(bounds.minimum_value) == int(bounds.maximum_value):
return [[
error.error(
source_file_name, error_source_location,
"Constant value {} of {} cannot fit in a 64-bit signed or "
"unsigned integer.".format(bounds.minimum_value, name))
]]
else:
return [[
error.error(
source_file_name, error_source_location,
"Potential range of {} is {} to {}, which cannot fit "
"in a 64-bit signed or unsigned integer.".format(
name, bounds.minimum_value, bounds.maximum_value))
]]
return []
def _check_bounds_on_runtime_integer_expressions(expression, source_file_name,
in_attribute, errors):
if in_attribute and in_attribute.name.text == attributes.STATIC_REQUIREMENTS:
# [static_requirements] is never evaluated at runtime, and $size_in_bits is
# unbounded, so it should not be checked.
return
# The logic for gathering errors and suppressing cascades is simpler if
# errors are just returned, rather than appended to a shared list.
errors += _integer_bounds_errors_for_expression(expression, source_file_name)
def _attribute_in_attribute_action(a):
return {"in_attribute": a}
def check_constraints(ir):
"""Checks miscellaneous validity constraints in ir.
Checks that auto array sizes are only used for the outermost size of
multidimensional arrays. That is, Type[3][] is OK, but Type[][3] is not.
Checks that fixed-size fields are a correct size to hold statically-sized
types.
Checks that inner array dimensions are constant.
Checks that only constant-size types are used in arrays.
Arguments:
ir: An ir_pb2.EmbossIr object to check.
Returns:
A list of ConstraintViolations, or an empty list if there are none.
"""
errors = []
traverse_ir.fast_traverse_ir_top_down(
ir, [ir_pb2.Structure, ir_pb2.Type], _check_allowed_in_bits,
parameters={"errors": errors})
traverse_ir.fast_traverse_ir_top_down(
# TODO(bolms): look for [ir_pb2.ArrayType], [ir_pb2.AtomicType], and
# simplify _check_that_array_base_types_are_fixed_size.
ir, [ir_pb2.ArrayType], _check_that_array_base_types_are_fixed_size,
parameters={"errors": errors})
traverse_ir.fast_traverse_ir_top_down(
ir, [ir_pb2.Structure, ir_pb2.ArrayType],
_check_that_array_base_types_in_structs_are_multiples_of_bytes,
parameters={"errors": errors})
traverse_ir.fast_traverse_ir_top_down(
ir, [ir_pb2.ArrayType, ir_pb2.ArrayType],
_check_that_inner_array_dimensions_are_constant,
parameters={"errors": errors})
traverse_ir.fast_traverse_ir_top_down(
ir, [ir_pb2.Structure], _check_size_of_bits,
parameters={"errors": errors})
traverse_ir.fast_traverse_ir_top_down(
ir, [ir_pb2.Structure, ir_pb2.Type], _check_type_requirements_for_field,
parameters={"errors": errors})
traverse_ir.fast_traverse_ir_top_down(
ir, [ir_pb2.Field], _check_field_name_for_reserved_words,
parameters={"errors": errors})
traverse_ir.fast_traverse_ir_top_down(
ir, [ir_pb2.EnumValue], _check_enum_name_for_reserved_words,
parameters={"errors": errors})
traverse_ir.fast_traverse_ir_top_down(
ir, [ir_pb2.TypeDefinition], _check_type_name_for_reserved_words,
parameters={"errors": errors})
traverse_ir.fast_traverse_ir_top_down(
ir, [ir_pb2.Expression], _check_constancy_of_constant_references,
parameters={"errors": errors})
traverse_ir.fast_traverse_ir_top_down(
ir, [ir_pb2.Enum], _check_that_enum_values_are_representable,
parameters={"errors": errors})
traverse_ir.fast_traverse_ir_top_down(
ir, [ir_pb2.Expression], _check_bounds_on_runtime_integer_expressions,
incidental_actions={ir_pb2.Attribute: _attribute_in_attribute_action},
skip_descendants_of={ir_pb2.EnumValue, ir_pb2.Expression},
parameters={"errors": errors, "in_attribute": None})
traverse_ir.fast_traverse_ir_top_down(
ir, [ir_pb2.RuntimeParameter],
_check_type_requirements_for_parameter_type,
parameters={"errors": errors})
return errors